It always confused me when my mom would ask someone what "percent" certain they were, and they would answer 80% or 90%. I thought, if you're certain, you're certain, and these people all must have an agreed upon number that would mean they are certain. Finally, my mom asked me the question one day, and I asked her "out of what number?" I thought it was a perfectly intelligent question (since the number could be anything) and she said 100. So I was 100% certain. What bothered me though, was that I would still hear other people quote other percents, yet my mom always told me the number was 100. It took me a while to realize you didn't always have to be 100% certain!
A childhood belief about counting

others believed things like this
- when i was little i believed that your social security number was the number you were born on the earth — christine
- When I was little I thought you could get arrested if you accidentally skipped a number while counting.— Hailey
- I thought everyone only had a set number of breaths before they died.
I breathed slowly for a long time.Anon - I used to believe there was a number "eleventeen". I could never quite work out where it went, though.— Matthew
- I used to think boys went "number two" with their pee pees. Anon
- I used to believe that twenty was the largest number in the universe.— Bernardo Fernandez